3B Scientific Air Cushion Plate - Handbuch (Seite 74)

23
Physical Experiments on the Air-Cushion Table
How to proceed:
Align the air-cushion table horizontally and attach
the magnetic barriers around the experiment
surface. Arrange the piston parallel to magnetic
barrier no. 2. The piston rod rests on the guide
piece for the magnetic piston, which has been
attached onto magnetic barrier no. 2 and ensures
its guidance. Arrange three of the hover discs near
barrier no. 1, the barrier with the slit for air ente-
ring from the impulse valve. Move the piston as
far as possible towards this barrier.
Turn the fan to a setting providing a strong airflow.
Now bring one of the remaining discs after the
other onto the experiment surface, making each
shoot in at the highest possible speed starting from
barrier no. 1. Observe the motions of the hover
discs and the piston.
Result:
The piston shifts through the impacts of the hover
discs at the rate at which the number of discs
increases. This causes an enlargement of the area
available to the hover discs.
Interpretation:
Increasing the number of molecules in a specific
gas volume causes a rise in pressure. If the ves-
sel containing the gas is equipped with a moving
piston, the volume of the gas will increase when
the number of molecules rises.
Note:
It is also possible to demonstrate the force acting
on the piston from the outside due to air pressure.
This is done by slightly tilting the experiment
surface so that the hover discs have to push the
piston up a slope to increase the area in size.
2.1.14 Diffusion of Gases
Components:
Air-cushion table with fan
Overhead projector
Magnetic barrier, long
2 Pieces
Magnetic barrier, short 2 Pieces
Magnetic piston l Piece
Hover disc, red 6 Pieces
Hover disc, green 6 Pieces
Model simulation
Real Object Model
Vessel containing Experiment surface
the gas of the air-cushion table
Walls of the vessel Magnetic barriers
Partition Magnetic piston
Molecules of Green hover disc
one gas
Molecules of the
Red hover disc
other gas
How to proceed:
Align the air-cushion table horizontally and insert
the magnetic barriers. Place the red discs in one
half of the experiment surface, near magnetic
barrier no. 1, and the green discs in the other half,
near barrier no. 2. Place the magnetic piston in
the center as a partition running parallel to barriers
no. 1 and 2.
Turn the fan to a low setting so that the hover discs
just lift off. Then quickly remove the piston and
observe the motions of the red and green discs.
Repeat the experiment using a stronger airflow
after placing the red discs close to barrier no. 1
and the green ones close to barrier no. 2.